Molecular cloning and biophysical characterization of CXCL3 chemokine

Integrative multi-omics analysis of radionuclide-induced intestinal injury reveals the radioprotective role of L-citrulline through histone H3-mediated Cxcl3

BACKGROUND

The widespread application of nuclear technology has markedly heightened the risk of extensive, uncontrolled exposure to radiation. Nevertheless, in contrast to external irradiation, the biological impacts and countermeasures against internal irradiation from radionuclides remain inadequately characterized.

METHODS

Mice were administered yttrium-90 (Y90) carbon microspheres via gavage at different dosages (0-5.0 mCi) to establish a radionuclides exposure model. A multi-omics analysis was employed to access alterations in gut microbiota, fecal and colonic metabolites profiles, and intestinal mRNA expression post-irradiation. The function of significant metabolite was validated at both cellular levels and organismal levels. Additionally, ChIP-Seq and RNA-Seq techniques were utilized to investigate the molecular mechanism underlying the actions of key metabolite.

RESULTS

Exposure to Y90 resulted in intestinal damage and hematological impairment. Multi-omics analysis revealed significant alternations of gut microbiota, fecal metabolites, colonic metabolites, and intestinal mRNA expression following internal radiation exposure. Notably, L-citrulline was identified as a metabolite with changes observed in both fecal and colonic tissues, demonstrating radioprotective properties in vitro and in vivo. Mechanistically, L-citrulline facilitated the citrullination of histone H3 at the 17th site (H3Cit17), and multiple mRNAs including C-X-C motif chemokine ligand 3 (Cxcl3), were transcriptionally regulated by H3Cit17 post L-citrulline treatment. Furthermore, Cxcl3 conferred protective effects for intestinal epithelial cells against ionizing radiation.

CONCLUSIONS

The research offers critical perspectives on the intestinal and gut microbiota's reaction to radionuclides exposure. It underscores the promise of L-citrulline as a radioprotective compound, which may have substantial ramifications for the formulation of strategies to mitigate radiation exposure.

Correlating transcription and protein expression profiles of immune biomarkers following lipopolysaccharide exposure in lung epithelial cells

Universal and early recognition of pathogens occurs through recognition of evolutionarily conserved pathogen associated molecular patterns (PAMPs) by innate immune receptors and the consequent secretion of cytokines and chemokines. The intrinsic complexity of innate immune signaling and associated signal transduction challenges our ability to obtain physiologically relevant, reproducible and accurate data from experimental systems. One of the reasons for the discrepancy in observed data is the choice of measurement strategy. Immune signaling is regulated by the interplay between pathogen-derived molecules with host cells resulting in cellular expression changes. However, these cellular processes are often studied by the independent assessment of either the transcriptome or the proteome. Correlation between transcription and protein analysis is lacking in a variety of studies. In order to methodically evaluate the correlation between transcription and protein expression profiles associated with innate immune signaling, we measured cytokine and chemokine levels following exposure of human cells to the PAMP lipopolysaccharide (LPS) from the Gram-negative pathogen Pseudomonas aeruginosa. Expression of 84 messenger RNA (mRNA) transcripts and 69 proteins, including 35 overlapping targets, were measured in human lung epithelial cells. We evaluated 50 biological replicates to determine reproducibility of outcomes. Following pairwise normalization, 16 mRNA transcripts and 6 proteins were significantly upregulated following LPS exposure, while only five (CCL2, CSF3, CXCL5, CXCL8/IL8, and IL6) were upregulated in both transcriptomic and proteomic analysis. This lack of correlation between transcription and protein expression data may contribute to the discrepancy in the immune profiles reported in various studies. The use of multiomic assessments to achieve a systems-level understanding of immune signaling processes can result in the identification of host biomarker profiles for a variety of infectious diseases and facilitate countermeasure design and development.

Targeting Members of the Chemokine Family as a Novel Approach to Treating Neuropathic Pain

Neuropathic pain is a debilitating condition that affects millions of people worldwide. Numerous studies indicate that this type of pain is a chronic condition with a complex mechanism that tends to worsen over time, leading to a significant deterioration in patients' quality of life and issues like depression, disability, and disturbed sleep. Presently used analgesics are not effective enough in neuropathy treatment and may cause many side effects due to the high doses needed. In recent years, many researchers have pointed to the important role of chemokines not only in the development and maintenance of neuropathy but also in the effectiveness of analgesic drugs. Currently, approximately 50 chemokines are known to act through 20 different seven-transmembrane G-protein-coupled receptors located on the surface of neuronal, glial, and immune cells. Data from recent years clearly indicate that more chemokines than initially thought (CCL1/2/3/5/7/8/9/11, CXCL3/9/10/12/13/14/17; XCL1, CX3CL1) have pronociceptive properties; therefore, blocking their action by using neutralizing antibodies, inhibiting their synthesis, or blocking their receptors brings neuropathic pain relief. Several of them (CCL1/2/3/7/9/XCL1) have been shown to be able to reduce opioid drug effectiveness in neuropathy, and neutralizing antibodies against them can restore morphine and/or buprenorphine analgesia. The latest research provides irrefutable evidence that chemokine receptors are promising targets for pharmacotherapy; chemokine receptor antagonists can relieve pain of different etiologies, and most of them are able to enhance opioid analgesia, for example, the blockade of CCR1 (J113863), CCR2 (RS504393), CCR3 (SB328437), CCR4 (C021), CCR5 (maraviroc/AZD5672/TAK-220), CXCR2 (NVPCXCR220/SB225002), CXCR3 (NBI-74330/AMG487), CXCR4 (AMD3100/AMD3465), and XCR1 (vMIP-II). Recent research has shown that multitarget antagonists of chemokine receptors, such as CCR2/5 (cenicriviroc), CXCR1/2 (reparixin), and CCR2/CCR5/CCR8 (RAP-103), are also very effective painkillers. A multidirectional strategy based on the modulation of neuronal-glial-immune interactions by changing the activity of the chemokine family can significantly improve the quality of life of patients suffering from neuropathic pain. However, members of the chemokine family are still underestimated pharmacological targets for pain treatment. In this article, we review the literature and provide new insights into the role of chemokines and their receptors in neuropathic pain.

C-X-C Motif Chemokine 3 Promotes the Inflammatory Response of Microglia after Escherichia coli-Induced Meningitis

Meningitis is a major clinical manifestation of Escherichia coli (E. coli) infection characterized by inflammation of the meninges and subarachnoid space. Many chemokines are secreted during meningitic E. coli infection, of which C-X-C motif chemokine 3 (CXCL3) is the most highly expressed. However, it is unclear how CXCL3 plays a role in meningitic E. coli infection. Therefore, this study used in vitro and in vivo assays to clarify these contributions and to identify novel therapeutic targets for central nervous system inflammation. We found a significantly upregulated expression of CXCL3 in human brain microvascular endothelial cells and U251 cells after meningitic E. coli infection, and the CXCL3 receptor, C-X-C motif chemokine receptor 2 (CXCR2), was expressed in microglia. Furthermore, CXCL3 induced M1 microglia by selectively activating mitogen-activated protein kinases signaling and significantly upregulating tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, nitric oxide synthase 2 (NOS2), and cluster of differentiation 86 (CD86) expression levels, promoting an inflammatory response. Our findings clarify the role of CXCL3 in meningitic E. coli-induced neuroinflammation and demonstrate that CXCL3 may be a potential therapeutic target for future investigation and prevention of E. coli-induced neuroinflammation.

Multi-omics blood atlas reveals unique features of immune and platelet responses to SARS-CoV-2 Omicron breakthrough infection

Although host responses to the ancestral SARS-CoV-2 strain are well described, those to the new Omicron variants are less resolved. We profiled the clinical phenomes, transcriptomes, proteomes, metabolomes, and immune repertoires of >1,000 blood cell or plasma specimens from SARS-CoV-2 Omicron patients. Using in-depth integrated multi-omics, we dissected the host response dynamics during multiple disease phases to reveal the molecular and cellular landscapes in the blood. Specifically, we detected enhanced interferon-mediated antiviral signatures of platelets in Omicron-infected patients, and platelets preferentially formed widespread aggregates with leukocytes to modulate immune cell functions. In addition, patients who were re-tested positive for viral RNA showed marked reductions in B cell receptor clones, antibody generation, and neutralizing capacity against Omicron. Finally, we developed a machine learning model that accurately predicted the probability of re-positivity in Omicron patients. Our study may inspire a paradigm shift in studying systemic diseases and emerging public health concerns.

Plasma CXCL3 Levels Are Associated with Tumor Progression and an Unfavorable Colorectal Cancer Prognosis

Background

The CXC chemokines belong to a unique family of chemotactic cytokines that influence the initiation, progression, and clinical outcome of many tumor types. Herein, we investigated the association of the CXC-chemokine ligand 3 (CXCL3) with tumor progression and an unfavorable prognosis for colorectal cancer (CRC).

Methods

The quantitative real-time polymerase chain reaction was used to explore the expression of CXCL3 in CRC tissue, adjacent tissue, and plasma. The usefulness of plasma levels of CXCL3 for the diagnosis of CRC was evaluated by receiver operating characteristic curve analysis. Pearson's correlation analysis assessed relationships among plasma CXCL3, cancer tissue CXCL3, and plasma carcinoembryonic antigen (CEA). Kaplan–Meier analysis was used to assess the survival of CRC patients with high and low expression levels of CXCL3. Survival differences were compared by log-rank test.

Results

Initial analysis of the GSE156720 dataset identified CXCL3 as the most enriched CXCL gene in CRC patients. Higher CXCL3 levels were detected in CRC tissue than in adjacent tissue (P < 0.001). Compared to healthy controls, CRC patient plasma CXCL3 levels were higher (P < 0.001). The area under the curve was 0.81 with a sensitivity of 0.71 and specificity of 0.82, distinguishing CRC from other tumor types. Plasma CXCL3 was positively related to CXCL3 in cancer tissue (r = 0.78, P < 0.01), and also to plasma CEA (r = 0.50, P < 0.01). Plasma CXCL3 was also related to tumor size (P = 0.034), staging (P < 0.001), tumor stage (P = 0.003), differentiation (P = 0.001), and lymph node metastasis (P = 0.007), but not to sex (P = 0.853), age (P = 0.691), tumor site (P = 1.347), or distant metastasis (P = 1.218).

Conclusions

CXCL3 levels were increased in CRC patients, with plasma CXCL3 levels associated with tumor progression and an unfavorable CRC prognosis. The results of this study suggest that plasma CXCL3 may be a novel diagnostic and prognostic biomarker for CRC.

Conserved Apical Proline Regulating the Structure and DNA Binding Properties of Helicobacter pylori Histone-like DNA Binding Protein (Hup)

Prokaryotic cells lack a proper dedicated nuclear arrangement machinery. A set of proteins known as nucleoid associated proteins (NAPs) perform opening and closure of nucleic acids, behest cellular requirement. Among these, a special class of proteins analogous to eukaryotic histones popularly known as histone-like (HU) DNA binding proteins facilitate the nucleic acid folding/compaction thereby regulating gene architecture and gene regulation. DNA compaction and DNA protection in Helicobacter pylori is performed by HU protein (Hup). To dissect and galvanize the role of proline residue in the binding of Hup with DNA, the structure-dynamics-functional relationship of Hup-P64A variant was analyzed. NMR and biophysical studies evidenced that Hup-P64A protein attenuated DNA-binding and induced structural/stability changes in the DNA binding domain (DBD). Moreover, molecular dynamics simulations and ¹⁵N relaxation studies established the reduced conformational dynamics of P64A protein. This comprehensive study dissected the exclusive role of evolutionarily conserved apical proline residue in regulating the structure and DNA binding of Hup protein as P64 is presumed to be involved in the external leverage mechanism responsible for DNA bending and packaging, as proline rings wedge into the DNA backbone through intercalation besides their significant role in DNA binding.

Comparison of the Effects of Chemokine Receptors CXCR2 and CXCR3 Pharmacological Modulation in Neuropathic Pain Model-In Vivo and In Vitro Study

Recent findings have highlighted the roles of CXC chemokine family in the mechanisms of neuropathic pain. Our studies provide evidence that single/repeated intrathecal administration of CXCR2 (NVP-CXCR2-20) and CXCR3 ((±)-NBI-74330) antagonists explicitly attenuated mechanical/thermal hypersensitivity in rats after chronic constriction injury of the sciatic nerve. After repeated administration, both antagonists showed strong analgesic activity toward thermal hypersensitivity; however, (±)-NBI-74330 was more effective at reducing mechanical hypersensitivity. Interestingly, repeated intrathecal administration of both antagonists decreased the mRNA and/or protein levels of pronociceptive interleukins (i.e., IL-1beta, IL-6, IL-18) in the spinal cord, but only (±)-NBI-74330 decreased their levels in the dorsal root ganglia after nerve injury. Furthermore, only the CXCR3 antagonist influenced the spinal mRNA levels of antinociceptive factors (i.e., IL-1RA, IL-10). Additionally, antagonists effectively reduced the mRNA levels of pronociceptive chemokines; NVP-CXCR2-20 decreased the levels of CCL2, CCL6, CCL7, and CXCL4, while (±)-NBI-74330 reduced the levels of CCL3, CCL6, CXCL4, and CXCL9. Importantly, the results obtained from the primary microglial and astroglial cell cultures clearly suggest that both antagonists can directly affect the release of these ligands, mainly in microglia. Interestingly, NVP-CXCR2-20 induced analgesic effects after intraperitoneal administration. Our research revealed important roles for CXCR2 and CXCR3 in nociceptive transmission, especially in neuropathic pain.

Lung Inflammatory Response to Environmental Dust Exposure in Mice Suggests a Link to Regional Respiratory Disease Risk

PURPOSE

The Salton Sea, California's largest lake, is designated as an agricultural drainage reservoir. In recent years, the lake has experienced shrinkage due to reduced water sources, increasing levels of aerosolized dusts in surrounding regions. Communities surrounding the Salton Sea have increased asthma prevalence versus the rest of California; however, a connection between dust inhalation and lung health impacts has not been defined.

METHODS

We used an established intranasal dust exposure murine model to study the lung inflammatory response following single or repetitive (7-day) exposure to extracts of dusts collected in regions surrounding the Salton Sea (SSDE), complemented with in vitro investigations assessing SSDE impacts on the airway epithelium.

RESULTS

In these investigations, single or repetitive SSDE exposure induced significant lung inflammatory cytokine release concomitant with neutrophil influx. Repetitive SSDE exposure led to significant lung eosinophil recruitment and altered expression of genes associated with allergen-mediated immune response, including Clec4e. SSDE treatment of human bronchial epithelial cells (BEAS-2B) induced inflammatory cytokine production at 5- and 24-hours post-treatment. When BEAS-2B were exposed to protease activity-depleted SSDE (PDSSDE) or treated with SSDE in the context of protease-activated receptor-1 and -2 antagonism, inflammatory cytokine release was decreased. Furthermore, repetitive exposure to PDSSDE led to decreased neutrophil and eosinophilic influx and IL-6 release in mice compared to SSDE-challenged mice.

CONCLUSION

These investigations demonstrate potent lung inflammatory responses and tissue remodeling in response to SSDE, in part due to environmental proteases found within the dusts. These studies provide the first evidence supporting a link between environmental dust exposure, protease-mediated immune activation, and respiratory disease in the Salton Sea region.

Single-cell transcriptome profiling reveals vascular endothelial cell heterogeneity in human skin

Vascular endothelial cells (ECs) are increasingly recognized as active players in intercellular crosstalk more than passive linings of a conduit for nutrition delivery. Yet, their functional roles and heterogeneity in skin remain uncharacterized. We have used single-cell RNA sequencing (scRNA-seq) as a profiling strategy to investigate the tissue-specific features and intra-tissue heterogeneity in dermal ECs at single-cell level.

Methods: Skin tissues collected from 10 donors were subjected to scRNA-seq. Human dermal EC atlas of over 23,000 single-cell transcriptomes was obtained and further analyzed. Arteriovenous markers discovered in scRNA-seq were validated in human skin samples via immunofluorescence. To illustrate tissue-specific characteristics of dermal ECs, ECs from other human tissues were extracted from previously reported data and compared with our transcriptomic data.

Results: In comparison with ECs from other human tissues, dermal ECs possess unique characteristics in metabolism, cytokine signaling, chemotaxis, and cell adhesions. Within dermal ECs, 5 major subtypes were identified, which varied in molecular signatures and biological activities. Metabolic transcriptome analysis revealed a preference for oxidative phosphorylation in arteriole ECs when compared to capillary and venule ECs. Capillary ECs abundantly expressed HLA-II molecules, suggesting its immune-surveillance role. Post-capillary venule ECs, with high levels of adhesion molecules, were equipped with the capacity in immune cell arrest, adhesion, and infiltration.

Conclusion: Our study provides a comprehensive characterization of EC features and heterogeneity in human dermis and sets the stage for future research in identifying disease-specific alterations of dermal ECs in various dermatoses.

Molecular insights into the differential structure-dynamics-stability features of interleukin-8 orthologs: Implications to functional specificity

Chemokines are a sub-group of chemotactic cytokines that regulate the leukocyte migration by binding to G-protein coupled receptors (GPCRs) and cell surface glycosaminoglycans (GAGs). Interleukin-8 (CXCL8/IL8) is one of the most essential CXC chemokine that has been reported to be involved in various pathophysiological conditions. Structure-function relationships of human IL8 have been studied extensively. However, no such detailed information is available on IL8 orthologs, although they exhibit significant functional divergence. In order to unravel the differential structure-dynamics-stability-function relationship of IL8 orthologs, comparative molecular analysis was performed on canine (laurasians) and human (primates) IL8 proteins using in-silico molecular evolutionary analysis and solution NMR spectroscopy methods. The residue level NMR studies suggested that, although the overall structural architecture of canine IL8 is similar to that of human IL8, systematic differences were observed in their backbone dynamics and low-energy excited states due to amino acid substitutions. Further, these substitutions also resulted in attenuation of stability and heparin binding affinity in the canine IL8 as compared to its human counterpart. Indeed, structural and sequence analysis evidenced for specificity of molecular interactions with cognate receptor (CXCR1) and glycosaminoglycan (heparin), thus providing evidence for a noticeable functional specificity and divergence between the two IL8 orthologs.

Elucidating the Molecular Interactions of Chemokine CCL2 Orthologs with Flavonoid Baicalin

An integrated and controlled migration of leukocytes is necessary for the legitimate functioning and maintenance of the immune system. Chemokines and their receptors play a decisive role in regulating the leukocyte migration to the site of inflammation, a phenomena often referred to as chemotaxis. Chemokines and their receptors have become significant targets for therapeutic intervention considering their potential to regulate the immune system. Monocyte chemoattractant protein-1 (MCP-1/CCL2) is a preeminent member of CC chemokine family that facilitates crucial roles by orchestrating the recruitment of monocytes into inflamed tissues. Baicalin (BA), a major bioactive flavonoid, has been reported to attenuate chemokine-regulated leukocyte trafficking. However, no molecular details pertaining to its direct binding to chemokine(s)/receptor(s) are available till date. In the current study, using an array of monomers/dimers of human and murine CCL2 orthologs (hCCL2/mCCL2), we have shown that BA binds to the CCL2 protein specifically with nanomolar affinity (K _d = 270 ± 20 nM). NMR-based studies established that BA binds CCL2 in a specific pocket involving the N-terminal, β1- and β3-sheets. Docking studies suggested that the residues T16, N17, R18, I20, R24, K49, E50, I51, and C52 are majorly involved in complex formation through a combination of H-bonds and hydrophobic interactions. As the residues R18, R24, and K49 of hCCL2 are crucial determinants of monocyte trafficking through receptor/glycosaminoglycans (GAG) binding in CCL2 human/murine orthologs, we propose that baicalin engaging these residues in complex formation will result in attenuation of CCL2 binding to the receptor/GAGs, thus inhibiting the chemokine-regulated leukocyte trafficking.

circMET promotes NSCLC cell proliferation, metastasis, and immune evasion by regulating the miR-145-5p/CXCL3 axis

In recent years, circular RNAs (circRNAs) have been increasingly reported to play a crucial role in the proliferation, migration, and invasion of non-small-cell lung cancer (NSCLC) cells. However, the circRNA MET (circMET) oncogenic mechanism that drives NSCLC development and progression remains largely unknown. In this study, the present results demonstrated that circMET expression was significantly higher in NSCLC tissues than in peritumoral tissues using quantitative real-time polymerase chain reaction. Notably, NSCLC patients with a large tumor diameter, poor differentiation and lymphatic metastasis had high RNA levels of circMET. Moreover, high circMET expression served as an independent risk factor for short overall survival (OS) and progression-free survival (PFS) in NSCLC patients. Next, we validated that circMET overexpression can enhance NSCLC cell proliferation, metastasis, and immune evasion in vitro. Mechanistically, our study uncovers that circMET acts as a miR-145-5p sponge to upregulate CXCL3 expression. Collectively, circMET regulates the miR-145-5p/CXCL3 axis and serves as a novel, promising diagnostic and prognostic biomarker in patients with NSCLC.

Dissecting the differential structural and dynamics features of CCL2 chemokine orthologs

Chemokines are a sub-group of cytokines that regulate the leukocyte migration. Monocyte chemoattractant protein-1 (MCP/CCL2) is one of the essential CC chemokine that regulates the migration of monocytes into inflamed tissues. It has been observed that the primary sequences of CCL2 orthologs among rodents and primates vary significantly at the C-terminal region. However, no structural details are available for the rodentia family CCL2 proteins. The current study unravelled the structural, dynamics and in-silico functional characteristics of murine CCL2 chemokine using a comprehensive set of NMR spectroscopy techniques and evolutionary approaches. The study unravelled that the N-terminal portion of the murine CCL2 forms a canonical CC chemokine dimer similar to that of human CCL2. However, unlike human CCL2, the murine ortholog exhibits extensive dynamics in the μs-ms timescales. The presence of C-terminal region of the murine CCL2 protein/rodentia family is highly glycosylated, completely disordered, and inhibits the folding of the structured CCL2 regions. Further, it has been observed that the glycosaminoglycan binding surfaces of these orthologs proteins are greatly differed. In a nut shell, this comparative study provided the role of molecular evolution in generating orthologous proteins with differential structural and dynamics characteristics to engage them in specific molecular interactions.

Unraveling the evolutionary origin of ELR motif using fish CXC chemokine CXCL8

Chemokines are chemotactic proteins involved in host defense through the migration of immune-regulatory cells to the site of infection. Interleukin-8 (CXCL8/IL8) is the most studied "ELR-CXC chemokine/neutrophil activating chemokine (NAC) that regulate neutrophil trafficking during infections and inflammation by binding to its cognate G-protein coupled receptors CXCR1/CXCR2. The "ELR" motif of NAC chemokines is essential for the CXCR1/CXCR2 receptor activation. In order to understand the evolutionary origin of "ELR" motif in the CXC chemokines, a thorough evolutionary study of CXCL8 gene from various fishes and primates was performed. Phylogenetic analysis revealed that the CXCL8 gene can be classified into four distinct lineages (CXCL8-L1a, CXCL8-L1b, CXCL8-L2, and CXCL8-L3), where CXCL8-L1a is the fastest evolving lineage and CXCL8-L3 is the slowest. Selection analysis suggested that The "ELR/DLR" motif containing branches (gadoid and coelacanth) are positively selected. The probable evolutionary trend of "ELR" motif suggested that this motif in ancestor CXCL8 is evolved from the GGR of Lamprey (Agnatha), followed by duplication giving rise to two main motifs in CXCL8 "NXH" in L3 lineage and "ELR/DLR" in L1a/L1b lineages. Although, structural analysis suggested that the overall topology of the CXCL8 proteins is similar, differences do exist at the individual structural elements among the members of different lineages. Functional distance analysis suggested that the CXCL8-L3 lineage is more distant compared to the CXCL8-L1a and L1b lineages from the inferred ancestor. Functional divergence analysis between different lineages suggested that most of the selected residues are important for receptor or glycosaminoglycan binding. Such a functional diversification can be attributed to the novel set of functions adopted by CXCL8 in various species.

Pharmacological Blockade of Spinal CXCL3/CXCR2 Signaling by NVP CXCR2 20, a Selective CXCR2 Antagonist, Reduces Neuropathic Pain Following Peripheral Nerve Injury

Recently, the role of CXCR2 in nociception has been noted. Our studies provide new evidence that the intrathecal administration of its CINC ligands (Cytokine-Induced Neutrophil Chemoattractant; CXCL1-3) induces pain-like behavior in naïve mice, and the effect occurring shortly after administration is associated with the neural location of CXCR2, as confirmed by immunofluorescence. RT-qPCR analysis showed, for the first time, raised levels of spinal CXCR2 after chronic constriction injury (CCI) of the sciatic nerve in rats. Originally, on day 2, we detected escalated levels of the spinal mRNA of all CINCs associated with enhancement of the protein level of CXCL3 lasting until day 7. Intrathecal administration of CXCL3 neutralizing antibody diminished neuropathic pain on day 7 after CCI. Interestingly, CXCL3 is produced in lipopolysaccharide-stimulated microglial, but not astroglial, primary cell cultures. We present the first evidence that chronic intrathecal administrations of the selective CXCR2 antagonist, NVP CXCR2 20, attenuate neuropathic pain symptoms and CXCL3 expression after CCI. Moreover, in naïve mice, this antagonist prevented CXCL3-induced hypersensitivity. However, NVP CXCR2 20 did not diminish glial activation, thus not enhancing morphine/buprenorphine analgesia. These results provide novel insight into the crucial role of CXCR2 in neuropathy based on CXCL3 modulation, which may become a potential therapeutic target in pain treatment.

Candida albicans Elicits Pro-Inflammatory Differential Gene Expression in Intestinal Peyer's Patches

The details of how gut-associated lymphoid tissues such as Peyer's patches (PPs) in the small intestine play a role in immune surveillance, microbial differentiation and the mucosal barrier protection in response to fungal organisms such as Candida albicans are still unclear. We particularly focus on PPs as they are the immune sensors and inductive sites of the gut that influence inflammation and tolerance. We have previously demonstrated that CD11c⁺ phagocytes that include dendritic cells and macrophages are located in the sub-epithelial dome within PPs sample C. albicans. To gain insight on how specific cells within PPs sense and respond to the sampling of fungi, we gavaged naïve mice with C. albicans strains ATCC 18804 and SC5314 as well as Saccharomyces cerevisiae. We measured the differential gene expression of sorted CD45⁺ B220⁺ B-cells, CD3⁺ T-cells and CD11c⁺ DCs within the first 24 h post-gavage using nanostring nCounter^® technology. The results reveal that at 24 h, PP phagocytes were the cell type that displayed differential gene expression. These phagocytes were able to sample C. albicans and discriminate between strains. In particular, strain ATCC 18804 upregulated fungal-specific pro-inflammatory genes pertaining to innate and adaptive immune responses. Interestingly, PP CD11c⁺ phagocytes also differentially expressed genes in response to C. albicans that were important in the protection of the mucosal barrier. These results highlight that the mucosal barrier not only responds to C. albicans, but also aids in the protection of the host.

An inter-switch between hydrophobic and charged amino acids generated druggable small molecule binding pocket in chemokine paralog CXCL3

Multigene families such as chemokines arose as a result of gene duplication events, followed by mutations and selection. GRO chemokines are three duplicated CXCL genes, comprising of CXCL1, CXCL2 and CXCL3 proteins. Comparative structural analysis of the two closely related paralog chemokines CXCL2 and CXCL3 in the current study indicated a variable electrostatic surface between them, and a specific hydrophobic pocket on the surface of CXCL3 that can bind naphthalene derivatives. Combined fluorescence and NMR analyses revealed that CXCL3 monomer can specifically bind to ANS (8-Anilinonaphthalene-1-sulfonic acid) with a stoichiometry of 1:1 by involving the residues belonging to the structural elements 3₁₀ helix and the α-helix. A close observation of the surfaces of these paralogs suggested that such a hydrophobic pocket is a resultant of inter-switch between a charged and a hydrophobic residue on the primary sequence of the two paralog proteins. Interestingly, the hydrophobic pocket is in the vicinity of GAG binding region of CXCL3, a molecular determinant in leukocyte trafficking. Such unique pockets/patches on specific chemokine surfaces can be exploited to design the naphthalene/small molecule based inhibitors against GAG binding to regulate their molecular interactions during the onset and progression of various types of cancers and inflammatory diseases.